Im pieceing my build together and a few shops asked about a girdle. So for a 1972 block 455 when is a grirdle needed after so much HP or if its going beyond a certain RPM. If Its not needed I dont see the point in spending the money but if its a real benefiting factor then I might do it.

 

from what ive read there good 2 have if your building a performace motor, i just ordered 1 with studs for around 250 heres the link, http://www.jsmachineoldsmobile.com/PRODUCTS.html

jim is very nice and helpful

 

do I need one for 500hp its not a windowed block

 

I would recommend at least strapping it for 500hp. Good insurance and not real expensive.

 

The 507 just has the straps,and it has been fine.If there was ti be a problem,it would have happened by now.I'm not too impressed with most of the Olds girdles out there anyway,but gaina,that's my opinion.The one I have for the 517 was made by Noel Sevigny,and is the best possible thing you can get,but the $2300.00 price turns just about everyone away.
A light weight rotating assembly will help take some stress off the mains.

 

Before you get started pickup a copy of How to Build Max-Performance Oldsmobile V-8"s by Bill Trovata. lots of good info regarding Olds blocks.

 

I have that book. Bill says a big block is reliable up to 650hp after that then u may want to consider a girdle. But everyone ask at the machine shops. And its so damn expensive and don't create power.

 

The first place you should put your money is into a lightweight rotating assembly, which generally means custom pistons and high-end rods. Only after you've done that should you put money into a girdle.

 

I agree 100%. Please don't forget about the crank shaft. Bill showed us with his EMC entry the limits of a stock crank. Close to the 700 HP level the crank started flexing causing premature bearing wear. With all the work needed to lighten, knife edge, stroke a cast crank , or whatever else you need to do at that power level, you'd be better off investing in a billet crank.

 

Yup,that's what I did.You can do everything possible to a factory crank,and you will be real close to the cost of a billet crank,but still have a heavy one,and not as strong as a billet piece.I also understand that billet cranks aren't for everyone.

 

How far do you guys think you can really go horsepower wise with a stock forged crank? This thread has really got me interested.

 

Forged or Nodular?

 

The N-cranks apparently start flexing at 600-650HP level,and that is with a lightweight rotating assembly.I doubt the 455 steel cranks will do much better,but a 65-67 400/425 forged crank can take more abuse.Those cranks are a better material than the 68 455 forged cranks.

 

I'm sure your probably right about the earlier forged cranks being made from better material, but don't you think that the longer stroke or rods is also much harder on the crank. I believe the earlier cranks were also lighter weight. Brian can you please tell us what are the significant differences between a factory steel crank versus a billet one? I have heard the billet ones come with an additional counter weight that helps even more with the balance. I can't speak from experience, yet. I've yet to stroke one. I do own a steel 455 crank though, it's the ugly one in Bill's book

 

Iam running a J&S Halo Girdle on the new motor,This is a 5-600HP combo that will be shifted at 6k or under............It has to be better than stock or straps IMHO,If I had a MAX HP build CNC girdles like Noels or Jeff Smiths ones would be the way to go........

 

Just an fyi, unless it's a lot heavier a longer rod typically produces less stress on a crank not more.

 

The earlier cranks did have shorter stroke,shorter counterweights,but they were NOT lighter.I think the better,denser material had something to do with that.If I remember correctly,the 400/425 cranks are around 80lbs,and I thought a typical N-crank was 74lbs.It's been awhile since I weighed one,or had to ship one.
The billet cranks can be ordered with the additional counterweight,hollow mains,and all the other little bells & whistles,along with it being made from a far better material.
billetcrank.jpg

 

I just weighed a CN crank, 68 pounds. Weighed a similar N crank that did not have all the rod throws drilled from the factory like the CN did, it weighed almost 71 pounds.
For comparison a cast BBC crank weighs 67.

 

Thanks for that info.Now I don't have to do it.